天文学家在包裹 Milky Way 中心超大质量黑洞 Sagittarius A* 的冷分子气体中发现一个巨大的锥形空洞，将其解读为热风外流约 20,000 年的证据。Sagittarius A* 距离地球约 26,000 光年，质量超过 4,000,000 个太阳；相较之下，超大质量黑洞通常定义为超过 100,000 个太阳质量。这一结果显示，该黑洞不仅吸入物质，也能抛出物质。

Mark Gorski 与 Lena Murchikova 使用智利北部 Alma radio telescope 的 66 座射电天线，分析黑洞中心 1 parsec（约 3 光年）内冷分子气体的 5 年观测资料。他们遮蔽黑洞本身的射电辐射后，看见边界清晰的锥形清空区，并以 Nasa 的 Chandra X-ray Observatory 交叉检验。研究发表于 The Astrophysical Journal Letters。

这项发现补足了先前对 Sagittarius A* 外流证据不足的问题，因为地球视线受尘埃、气体与碎屑遮挡，而且黑洞处于相对不活跃的 quiescent state。其他超大质量黑洞的风已被观测到，例如距离 53,000,000 光年的 M87。研究者认为，超新星或环绕恒星造成的热或风不符合观测；最重要的趋势是风稳定而非爆发，显示黑洞持续塑造周围环境。

Astronomers found a vast cone-shaped void in the cold molecular gas around Sagittarius A*, the supermassive black hole at the centre of the Milky Way, and interpret it as evidence of a hot wind flowing outward for about 20,000 years. Sagittarius A* lies about 26,000 light years from Earth and has a mass greater than 4,000,000 Suns; by comparison, supermassive black holes are generally defined as exceeding 100,000 solar masses. The result shows that this black hole not only consumes matter but also expels it.

Mark Gorski and Lena Murchikova used the 66 radio antennas of the Alma radio telescope in northern Chile to analyse five years of observations of cold molecular gas within 1 parsec, about 3 light years, of the black hole’s centre. After blocking the black hole’s own radio emissions, they saw a sharply bounded conical clearing and cross-checked it with Nasa’s Chandra X-ray Observatory. The study was published in The Astrophysical Journal Letters.

The discovery fills a gap in earlier evidence for outflows from Sagittarius A*, because Earth’s view is obscured by dust, gas and debris, and the black hole is in a relatively inactive quiescent state. Winds from other supermassive black holes have been observed, including in M87, 53,000,000 light years away. The researchers argue that heat or wind from a supernova or orbiting stars does not match the observations; the key trend is that the wind is steady rather than explosive, showing that black holes continuously shape their surroundings.